There are two common types of photovoltaic (solar) modules in use today. The first type of photovoltaic module utilizes a semiconductor wafer as a substrate and the second type of photovoltaic module utilizes a thin film of semiconductor that is deposited on a suitable substrate.
Semiconductor wafer type photovoltaic modules typically comprise the crystalline silicon wafers that are commonly used in various solid state electronic devices, such as computer memory chips and computer processors. This conventional design, while useful, is relatively expensive to fabricate and difficult to employ in non-standard applications.
Thin film photovoltaics, on the other hand, can incorporate one or more conventional semiconductors, such as amorphous silicon, on a suitable substrate. Unlike wafer applications, in which a wafer is cut from an ingot in a complex and delicate fabrication technique, thin film photovoltaics are formed using comparatively simple deposition techniques such as sputter coating, physical vapor deposition (PVD), or chemical vapor deposition (CVD).
While thin film photovoltaics are becoming more viable as a practical photovoltaic option to wafer photovoltaics, improvements in the efficiency, durability, and manufacturing expense are needed in the art.
One particularly persistent problem that has been encountered in the manufacture of thin film photovoltaic modules is the difficulty in obtaining an acceptable lamination of the polymeric layer, which is typically provided in sheet form, when a bus bar is present. A failure to properly de-air the bus bar region of the module during fabrication frequently results in an unusable product.
Accordingly, what are needed in the art are improved methods and constructions for producing easily manufactured and stable thin film photovoltaic modules.